Soneil charging curves are incorrect for AGMs?

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andrew
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Soneil charging curves are incorrect for AGMs?

UPDATE: 4/2/08 Click here. The Soneils appear to be doing two stage constant voltage charging, which is specified in the B&B technical manual. So the Soneils appear to have a suitable algorithm, though I wouldn't consider it optimal.

I was looking at buying six 12v chargers for my motorcycle. I've decided that my Zivan in combination with powercheqs is not satisfactory, and will reduce the life of my batteries severely.

At first glance these 1214S Soneils are ideal: http://www.electricrider.com/chargers/specsheets/1214s.pdf

But the charging curve is different from that specified from the B&B spec sheet. The CV stage needs to be 14.4-15v until the current tapers off to about .01 CA or .35 amps (35ah batteries).
http://www.bb-battery.com/productpages/EVP/EVP35-12H.pdf

The soneil 1214s, and a few others that I reviewed (4808SRF, 1212SR, 1206S) all hold the voltage constant at 14.4v ONLY until the current drops to .5CC (or half of what the constant current mode is for that particular charger). Then they reach what's called the "switch point", and they all drop the voltage to 13.8v indefinitely in float mode. They don't stay in the CV stage long enough.

This is insufficient for cycle use of my batteries according to the spec sheet linked above. I reviewed the spec sheets of some other AGM batteries.

Power Sonic PS-12350 (35 ah 12v)

CHARGING
Cycle Applications: Limit initial current to 10A. Charge until battery
voltage (under charge) reaches 14.40 to 14.70 volts at 68oF (20oC).
Hold at 14.40 to 14.70 volts until current drops to approximately 350mA.

Concord Sun Xtender Service Instructions:

# Set the charge voltage to 2.37 to 2.40 V./cell (14.2 to 14.4 V. for a 12 volt battery).
# Charge the battery until the charger reaches the 2.37 to 2.40 V./cell (14.2 to 14.4 for a 12 volt battery) and leave the battery on charge for an additional 4 to 6 hours before removing it from the charger.
# Alternately, the battery can be charged to the voltage setting [2.37 to 2.4 vpc] until the current from the charger drops to 0.5 A. per 100 Ampere Hour rating of the battery.

And this is interesting from the Odyssey Technical Manual:

If the charger has a timer, then it can switch from
absorption mode to float mode when the current drops
to 0.001C10 amps. If the current fails to drop to 0.001C10
amps, then the timer will force the transition to a float
charge after no more than 8 hours. As an example, for a
PC1200 battery [44 ah 12v battery], the threshold current should be 44mA.
Another option is to let the battery stay in the absorption
phase (14.7V or 2.45 VPC) for a fixed time, such as 6-8
hours, then switch to the continuous float charge.

...

Because the charger in Design 3 does not have a timer,
the threshold current to trigger the switch from the
absorption phase to the temperature-compensated float
charge phase is kept relatively high [at .10 C10]. Note that in this
design the battery will not be fully charged when the
charger switches to the float charge phase. A minimum
of 16-24 hours on float will be required to complete the
charge.

From this I can conclude:

1. Some Soneil chargers may not be charging AGM batteries in accordance with their manufacturer spec for cycle use. The consequences are unknown, but this may have an impact on cell balance, by not being able to charge all of the cells to 100% in a reasonable amount of time.

2. A full charge may require the charger to be left on much longer than after the light turns green. How much longer depends, but this may be longer than 24 hours.

fcherny
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Re: Soneil charging curves are incorrect for AGMs?

Andy of EVTA recommends leaving the Soneil charger plugged in while the Z20 is not in use. Do you think that's why?

andrew
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Re: Soneil charging curves are incorrect for AGMs?

fcherny, that may be why. I'm sure EVTA would've recognized this during testing. I'm trying to get in contact with Soneil to figure this out.

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andrew
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Re: Soneil charging curves are incorrect for AGMs?

In B&B's Technical Manual, it mentions two stage constant voltage charging on page 13. That appears to be what the Soneils are doing.

Their spec says that the switching point should be .04 to .08C amps, so the Soneil switching point is probably high for small batteries depending on the charger.

I don't have any information to compare this charging method to the traditional CV method, but I believe it will reduce the risk of thermal runaway. It will increase the amount of time that the charger needs to be plugged in to ensure full charge of all of the cells in a battery. And, it may increase the risk of the electrolyte being vented over time.

I prefer to have the charger shut off at end of charge, and most high-quality chargers do not maintain a float voltage, but charge at somewhere around 2.45 vpc CV, until the battery is fully charged then shut off, and monitor the battery voltage to pulse a float charge when needed. That's what the Vector, and Zivan chargers do.

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[url=/forum-topic/motorcycles-and-large-scooters/588-fixing-my-chinese-scooter]900 watt scooter[/url]
Pic from http://www.electri

jbird
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Re: Soneil charging curves are incorrect for AGMs?

I have been using the Soneil 4808srf for over two years on a Panterra Retro 750W Scooter with a 48V 20AH battery pack made up of four B&B BP17-12. I leave the charger plugged in almost continuously and have averaged probably 18+hrs a day since. I looked at the specifications for the charger and tested the charger with two multimeters (one used as a voltmeter and one as a ammeter.) The charger would charge up to 56.4V at 3.5A (constant current) then maintain 56.4V at 3.5A (constant current and constant voltage) then maintain 56.4V while the current started to decrease (constant voltage) and finally switch to 55.2V (float voltage) once the current reached 1.75A. The charge current then would slowly reduce over 6-8 hours to a couple hundred milliamps. This charge scheme has not caused my batteries to vent gas at all and keeps then usually within 0.08V of each other (just checked again after 1700 miles.) The originally batteries were quickly killed by a "cheap" chinese charger that would charge to over 60V (I recorded as high as 61.2V) the batteries would gas regularly during summer especially sitting outside in the sun at work while charging. This charger also would not switch to float until the current was about 0.18A. This charger has been permanently sidelined as a result and is only kept as a "last resort" emergency backup. The Soneil has worked so well that I bought another as backup anyway. I believe EVT America's charger for the Z20 may have the same charge scheme except for being 60V. In this case, it will not only be okay to leave it plugged in all the time but better for the batteries as it will decrease the likelihood of venting precious gas from the batteries and will allow for better cell equalization across the battery string. The only precautions I have are using a quality surge protector along with a large uninterruptible power supply (1500VA pure sine wave.) A good cheap way to know for sure what the charger is doing is to use multiple multimeters to measure total amps, total volts, +/- individual battery voltages (alternatively a Paktrakr although expensive) and have a lot of patience.

fisher727
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Re: Soneil charging curves are incorrect for AGMs?

jbird

I have heard that Soneil chargers have not temperature compensation. Have you observed different charge voltages at different temperatures.

Eric Fisher
siliconebatteriesusa.com

jbird
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Re: Soneil charging curves are incorrect for AGMs?

There is no actual temperature compensation on the Soneil chargers commonly sold. To compensate for this the bulk charge maximum voltage is adjusted down to 14.4V per 12 volt battery to minimize overcharge risk under hot conditions even though cyclic use usually is suggested to be from 14.7V to 15.0V for an AGM battery at room temperature. This makes leaving the charger connected for a prolonged time imperative during the winter after a discharge to avoid chronically undercharging the batteries. The float voltage is a little tricky because it is not as critical to have temperature compensation under this charge scheme. Normally batteries have a higher voltage when cold than when hot. The charge voltage observed during float charging does vary quite a bit with temperature. For example, during the winter with temperature around freezing the float voltage on my charger would go up as high as 56V. In the summer with temperatures around 100 degrees F the voltage would go down as low as 54.6V. I ride year round and have noticed performance changes related to temperature as well. For example in very cold weather scooter would go faster (top speed) initially but voltage sag would set in earlier and progress more quickly than in summer.

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